[Haskell-cafe] Memory consumption issues under heavy network throughput/concurrency loads

Kazu Yamamoto (=?iso-2022-jp?B?GyRCOzNLXE9CSScbKEI=?=) kazu at iij.ad.jp
Wed Jul 16 01:04:15 UTC 2014


>     https://github.com/gregorycollins/ghc-echo-leak-bug
> The revised echoserver is fine on my machine (stable at 22MB resident) but *the
> echo client leaks*. Happens with/without -O2 on GHC 7.8.3 for OSX.

I looked at your code very quickly.
What happens if you replace "replicateM" and "mapM_" to recursions?
(Especially I don't trust replicateM in IO.)

Also, we need to confirm that atomicModifyIORef' does not really leak

> Kazu, I think there's a good chance this is a bug in the multicore IO
> manager, the test code is doing little more than write + read + threadDelay.

If the space leak also happens with GHC 7.6.3, it is not specific to
the multicore IO manager. But the old/new IO manager might have
potential space leak.


I'm running Mighty 3 (based on WAI) compiled with GHC 7.8.x for a long
time. But I don't see any space leak at all.


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